/*
 * Copyright 2002-2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.messaging;

/**
 * Defines methods for sending messages.
 *
 * @author Mark Fisher
 * @since 4.0
 */
@FunctionalInterface
public interface MessageChannel {

    /**
     * Constant for sending a message without a prescribed timeout.
     */
    long INDEFINITE_TIMEOUT = -1;


    /**
     * Send a {@link Message} to this channel. If the message is sent successfully,
     * the method returns {@code true}. If the message cannot be sent due to a
     * non-fatal reason, the method returns {@code false}. The method may also
     * throw a RuntimeException in case of non-recoverable errors.
     * <p>This method may block indefinitely, depending on the implementation.
     * To provide a maximum wait time, use {@link #send(Message, long)}.
     *
     * @param message the message to send
     * @return whether or not the message was sent
     */
    default boolean send(Message<?> message) {
        return send(message, INDEFINITE_TIMEOUT);
    }

    /**
     * Send a message, blocking until either the message is accepted or the
     * specified timeout period elapses.
     *
     * @param message the message to send
     * @param timeout the timeout in milliseconds or {@link #INDEFINITE_TIMEOUT}
     * @return {@code true} if the message is sent, {@code false} if not
     * including a timeout of an interrupt of the send
     */
    boolean send(Message<?> message, long timeout);

}
